If you manufacture your own wheels, there is an easy way to make your wheels round. Use a screw that matches the wheel's hole size, two large washers and a nut to attach the wheel to a power drill or drill table. Then fix the power drill onto a clamp or some other attachment surface. As the drill turns, use a chisel to work on the wheel. Only use a corner of the chisel to begin the process, and never apply too much force. As long as the process is gradual, the resulting wheel is always round because of the rotation of the drill.